Electrical wiring conduit



May 17, 1932 G. L. CHAMBERLAIN ET AL. 1,859,259

ELECTRICAL WIRING' CONDUIT Filed July 8, 1929 Patented May l?, 1932 entre srArEs GEORGE L. CHAMBERLAIN AND G'USS I-I. GNEISS, `Oli CHICAGO,

ILLINOIS; SAID G'NEISS isere-Non 'ro SAID GHAMBERLAIN ELECTRICAL WIRING CONIITU'II.'4

Y Application filed July 8,

installed in the floors of building structures and usually are embedded beneath the surface of the floor. These ducts are usually made of metal and, in some cases, of compressed fibre or the like, and are originally fi laid as a permanent part of the system, but

having provision fortapping into the ducts at many different places throughout the length thereof where outlets for the conductors are required. In the original installation fittings are attached to these ducts insofar as the desired locations are known at the time of installation. However, additional connections may be made after the floor is completed by cutting into the Hoor to n expose the conduit at the point where the outlet fitting is tobe applied and patching the iioor after the connection has been completed.

As above stated, the conduits or ducts are usually made of metal or compressed fibre and, as a matter of economy, vand also to minimize weight, the walls of the conduits are usually of relatively thin gage. Consequently, owing to the rough character of the work and methods of constructing` concrete iioors the conduits or ducts become damaged and deformed to a considerable extent and, furthermore, nails are accidentally driven into the top walls of the ducts in nailing the usual wooden iinishing iioor material in place.

The present invention has for its principal object to produce a novel conduit or duct tube, preferably of substantially rectangular cross section, and having an armored top wall which will permit of the bottom and side walls being of relatively thin gage, and yet the structure as a whole is rigid to a considerable degree to withstand the rough usage to which it may be subjected, and is not easily punctured, and a relatively thick body is afforded for the screw-threading of the outlet openings in which the usual fittings are attached. Another object of the invention, in addition to the armored and stiffening fea- 1929. semi nof 376,769.

tures above noted, is to avoid protuberances on the outer face of the top wall of the conduit or duct which ordinarily occur due` to the necessity of flanging the portion fof the top wall around the usual tap openings pro-- vided in the relatively thin walled conduits or ducts for the purpose of providing suiicient screw threads to attach the outlet ittings thereto. Other objects and advantages to be attained will hereinafter more rfully appear.

In the accompanying drawings, illustrating practical adaptations of the invention,-V

Fig. l 1s a perspective view of a preferred form of 'the conduit or duct;

` Fig. 2 is a fragmentary view, on an enlarged scale, partly 1n side .elevation and partly in longitudinal section, illustrating the manner of coupling two of the conduits or ducts together in endwise relation;

F ig. 3 is a cross section through the duct on an enlarged scale; and. 1

Fig. 4 is a cross section of a modified duct structure. 'v

Referring now to the drawings, the nu- `meral 5 illustrates a duct ofpreferred'cross section and shown more particularly in detial in Fig. 3. As shown, this duct is of substantially rectangular form in cross section, it having a relatively thinbottom wall Gand side walls 7, and a relatively thick top wall 8.

The two opposite upper corner portionsof the duct are rounded off or tapered, as at 9, said corner portions being thus shaped prilmarily to deflect nails which mightotherwise puncture the conduit in theregion thereof, the relatively thick intermediate body of the top wallalso offering considerable resistance to nails being driven there against. Y

In addition to serving as a puncture-proof armor, thegrelatively thickened top wall 8 prevents collapsing of the lwall to a considerable degree and yat thesame time stiifens the structure so that lthe conduit is. not easily bent in a lateral direction, yet under certain conditions which makeit necessary the duct may be bent when due force is applied.

The tube may be drawn or otherwise formed or molded in a lsingle piece without seams or, in some cases, the `bottom and side v Fig. 3. Instead of rounding the upper'cord ltions of said tube tapered to afford delecting adjoining ldefined by the appended claims.

walls may be formed in channel shape from a single sheet of metal of a certain gage and the top wall produced separately of a relatively heavier gage and the two sections` then welded together at the meeting marginal portions, somewhatV as indicated along the seam line 10 of the modication illustrated in Fig. 4 of the drawings.Y In this modification the cross sectional form of the duct is somewhat different from that illustrated in ners of the duct, as at 9, they are -chamfere or beveled, as at 11, the effect being vsubstantially the same in that the beveled portion 11 will serve to deflect nails and, at the same time, an arched effect for the top Vwall is maintained in the structure. Y

In practice the ducts willbe madein unitary lengths,and at regular intervals .the to wall is provided with openings 12 whic are internally screw-threaded for the attachment ofthe usual outlet fittings, and those openings which are ynot used for Aoutletsare normally closed by removable plugs 13 which are 4secured therein instead of the said fittings.v The meeting portions of duct sections Vin the system as installed are attached together by a coupling sleeve 11i whose walls Aare preferably of the same gage throughout and whose interior contour is .a counterpart of-'the exterior contour of the duct sections. f The coupling sleeve 14C is provided with apertures to register rwith corresponding apertures 15 in the top wallsV of the duct sections near ythe "ends thereof for the reception ofV securing bolts 16. This coupling `member is also .provided with a socket 17 at the middle thereof for the Vattachr-nent of -a `marker for the Vpurpose of finding vthe location ofthe several vplugged outlet openings' aftei` the ductshave been enibedded and concealed within the floor structure. However, the structure and function of the coupling element 14 is not concerned in A the invention as claimed in the present application, but is subject-matter of a co-pen'ding application for Letters Patent and claimed separately therein, said application being filed of even date with the present application and bearing Serial Number 37 6,7 71, and resulting inv Letters Patent No.

1,825,049, issued September 29, 1931.

Obviously, the structure admits of considerable modification without departingk from the spirit andscope of the invention as tion, therefore, is not limited tothe specific construction Vand .arrangement rshown in the accompanying drawings.V y

Having `thus described our invention,

ters Patent is :v

yf1. A duct member of the character .de-v

the upper tapered to .afford deflecting surfaces and 'the .intermediate body portion ofthe The invenf 3. In a duct of 'the character described, ank

integrally formed tube of substantially ,rectangular cross'section, said tube having relatively th'n bottom and side walls, and a relatively thick top wall, the upper corner porsurfaces.

4. In a duct of lthe character described, an integrally formed metal tube of substan- Janvd side walls of said tube being of YrelativelyV thin gage, and the top wall being of relatively thickv gage, theupper corner portions 'of said tube being tapered to afford deilecting surfaces and the intermediate body portion of the top rwall 'being provided at intervals throughout lthe length o'f the tube with outlet openings having provision for `direct attachment of removable plug elements and outlet `fitting extensions interchangeably therein.

"tially rectangular ACross sectionfthe bottom V5. In a duct ofthe character described, an

integrally formed metal tube of substantially rectangular cross section, the 'bottom and side walls of said V-tube 'being of relatively thin gage,

and Vthe top wall being arched and the ymiddle portion tliereofjr-elatively thick, corner portions of said tube being top wall being provided at intervals throughout the 'length of the tube with outlet openings, said outletV `openings being internally screw threaded for the direct attachment of correspondingly threaded removable plugs and outlet fitting, extensions interchangeable therein.` f Y Y l In. testimony whereofwe have signed our names `to this specification. i Y Y GEORGE CHAMBERLAIN.

GUSS I-I.,GNEISS. Y

whatV i we claim as new and desire to secure by Let- 

